Fellous A, Prasad V, Ohayon R, Jordan M A, Ludueña R F
Unité de Recherche sur la Glande Thyroide et la Régulation Hórmonale, INSERM, Bicêtre, France.
J Protein Chem. 1994 May;13(4):381-91. doi: 10.1007/BF01901694.
Microtubule-associated proteins (MAPs) can promote microtubule assembly in vitro. One of these MAPs (MAP2) consists of a short promoter domain which binds to the microtubule and promotes assembly and a long projection domain which projects out from the microtubule and may interact with other cytoskeletal elements. We have previously shown that MAP2 and another MAP, tau, differ in their interactions with tubulin in that tau, but not MAP2, promotes extensive aggregation of tubulin into spiral clusters in the presence of vinblastine and that microtuubles formed with MAP2 are more resistant than those formed with tau to the antimitotic drug maytansine [Luduena, R. F., et al. (1984), J. Biol. Chem. 259, 12890-12898; Fellous, A., et al. (1985), Cancer Res. 45, 5004-5010]. Here we have used chymotryptic digestion to remove the projection domain of MAP2 and examined the interaction of the digested MAP2 (ctMAP2) with tubulin in the presence of vinblastine and maytansine. We have found that ctMAP2 behaves very much like tau, but not like undigested MAP2, in the presence of vinblastine, in that ctMAP2 causes tubulin to polymerize into large clusters of spirals. In contrast, microtubule assembly in the presence of ctMAP2 is much more resistant to maytansine inhibition than is assembly in the presence of tau or undigested MAP2. Our results suggest that the projection domain of MAP2 may play a role in the interaction of tubulin with MAP2 during microtubule assembly.
微管相关蛋白（MAPs）可在体外促进微管组装。其中一种MAP（MAP2）由一个与微管结合并促进组装的短启动子结构域和一个从微管伸出并可能与其他细胞骨架成分相互作用的长突出结构域组成。我们之前已经表明，MAP2和另一种MAP，即tau，在与微管蛋白的相互作用上存在差异，具体表现为在长春花碱存在的情况下，tau能促进微管蛋白广泛聚集成螺旋簇，而MAP2则不能，并且由MAP2形成的微管比由tau形成的微管对抗有丝分裂药物美登素更具抗性[卢德埃纳，R.F.等人（1984年），《生物化学杂志》259卷，12890 - 12898页；费卢斯，A.等人（1985年），《癌症研究》45卷，5004 - 5010页]。在此，我们用胰凝乳蛋白酶消化去除MAP2的突出结构域，并检测了消化后的MAP2（ctMAP2）在长春花碱和美登素存在的情况下与微管蛋白的相互作用。我们发现，在长春花碱存在的情况下，ctMAP2的行为与tau非常相似，而不像未消化的MAP2，因为ctMAP2会导致微管蛋白聚合成大的螺旋簇。相比之下，在ctMAP2存在的情况下微管组装比在tau或未消化的MAP2存在的情况下对美登素抑制的抗性要强得多。我们的结果表明，MAP2的突出结构域可能在微管组装过程中微管蛋白与MAP2的相互作用中发挥作用。
